M ore than 10 studies, including one that was published a few months ago in The New England Journal of Medicine, suggest that a high insulin level is a primary risk factor in heart disease. Excess insulin affects hormones that cause blood platelets to clot and clog arteries. No one has discovered a drug that will lower insulin levels. Only food can control its production.

So I set out to create a diet that would not only stabilize my own insulin levels and prolong my life but would help others as well.

The result? At age 49, after eight years of following my eating plan, I have the heart of a 25-year-old, according to my doctors. What's more, I dropped 30 pounds in the process and have kept the weight off. And my body fat is at a percentage (15%) that is considered ideal for me.

CUT BACK ON CARBOHYDRATES

US guidelines recommend that people eat a diet composed of about 70% carbohydrates, only 15% protein and 15% fat. But Americans haven't slimmed down as a result. Instead, most have stuffed themselves on complex carbohydrates, such as bread, potatoes and grains, and fattened up at epidemic proportions.

This type of carbohydrate-loading increases insulin levels in the blood, which in turn builds body fat. When insulin levels are high, the body cannot effectively burn stored fat.

My plan calls for a diet that derives 30% of its calories from protein, 40% from carbohydrates and 30% from fat. This balance ensures that insulin levels remain in an acceptable zone, which is not too much and not too little since you need a certain amount of insulin to maintain good health.

STEPS TO TAKE

My diet's eating plan is based on protein needs rather than total caloric needs. Once you determine how much protein you should consume, you can add a reasonable amount of 'good' carbohydrates and beneficial fats for health and weight control. Strategies...

Concentrate on protein. Although the US government advises adults to consume about 56 grams of protein daily, that is based on the needs of a 154-pound, sedentary male who has 23% body fat. Protein requirements can vary dramatically from person to person. How much you need depends on your height, weight, percentage of body fat and level of physical activity.

Examples: A six-foot, 185-pound man who exercises aerobically for 30 minutes a day and has 15% body fat needs about 120 grams of protein daily to maintain his muscle mass. A physically active 125-pound woman who is five-feet, five inches tall with 22% body fat requires about 70 grams of protein a day.

The higher your body fat and the lower your physical activity, the less protein you need. Note: There are about 15 to 25 grams of protein per three ounces of cooked meat, poultry or fish.

Calculating your body fat is complex. Speak with your doctor, or see the appropriate tables in my book The Zone.

Fill up on 'good' carbohydrates. All carbohydrates are not necessarily equal. High-density carbohydrates found in grains, pasta, bread, cereal, rice and potatoes enter the bloodstream too quickly, boosting insulin levels.

Low-density carbohydrates, like many vegetables and fruits, enter the bloodstream more slowly, so insulin levels don't shoot up.

The key is to limit your intake of high-density carbohydrates.

Example: Have two cups of steamed vegetables plus only one-quarter cup of pasta rather than a huge plate of pasta.

Add some 'good' fat to your diet. Fat has gotten a bad rap. Saturated fats, which are found in red meats, egg yolks, whole milk products and butter, have been linked to heart disease and various cancers, so they should be restricted.

Monounsaturated fats, which are found in olive oil, macadamia and pistachio nuts, almonds, cashews and avocados, not only enhance health but also slow the rate at which carbohydrates enter the bloodstream, thereby lowering insulin levels. The same is true of fish oil, the best source of which is fish like salmon.

Every meal and snack should contain some monounsaturated fat.

Eat three meals and two snacks a day. Just be sure all meals and snacks contain protein, carbohydrate and fat. Never eat carbohydrates alone. They will cause your insulin levels to skyrocket.

An ideal dinner might consist of four ounces of roasted, skinless chicken breast, fish or white-meat turkey surrounded by three cups of steamed, herb-seasoned vegetables.

You'll need to add a little monounsaturated fat to top off the meal, so drizzle one-third teaspoon olive oil over the vegetables or dress them with a tablespoon of slivered almonds.

Limit alcohol and caffeine. Beer, wine and hard liquor have the same effect on insulin levels as carbohydrates. Also, limit intake of caloric beverages such as juice and soda.

If you plan to have a drink with dinner, cut back on your allotted food carbohydrates.

Example: Instead of three cups of steamed vegetables at dinner, have only one-and-a-half cups.

If you drink alcohol, always team it with a protein 'chaser,' like a piece of low-fat cheese. Protein stimulates production of a hormone that reduces insulin levels. Caffeine in coffee, tea and colas also stimulates insulin production.

Switch to decaffeinated coffee and tea. If you must have coffee, have it with a healthy breakfast with the right amount of protein, carbohydrates and fats.

Exercise daily. Aside from burning calories and toning the body, aerobic exercise, such as walking, swimming, biking and working out on a treadmill, lowers insulin levels.

Don't follow your workout with a low-fat, carbohydrate-rich bagel that will cause insulin to soar. If you're ravenous after exercising, have a snack 30 to 40 minutes before your workout to prevent post-exercise carbohydrate cravings.

Healthy snack choice: One ounce of turkey breast and a piece of fresh fruit.